Method and device for producing endless drive belts

ABSTRACT

The endless drive belt is produced by winding a pre-formed load-carrying member comprising a cord embedded in a solid but softenable elastic material along and around a surface of an endless compression member belt also comprising a solid but softenable elastic material, thereby forming layer comprising a plurality of turns, and by simultaneously causing said turns to become intimately bonded to said surface. Said bonding is achieved by applying mutual pressure between said turns and said surface during winding and by selectively softening the surface layers of both said load-carrying member and said endless compression member belt which re to come into contact with each other, just prior to coming into contact with each other. The material of said surface layers is allowed to fuse. Said turns of said load-carrying member are further allowed to be partially impressed in said surface of said endless compression member belt. Softening may be carried out by the application of heat and/or the application of an adhesive. A device for carrying out the above method is also disclosed. With the device disclosed endless drive belts may be easily produced in-house at the time they are required at any size and at minimal costs and capital outlay.

This is a division of co-pending application, Ser. No. 795,298, filedNov. 20, 1991 now U.S. Pat. No. 5,129,866, which, in turn, is acontinuation of U.S. application Ser. No. 526,562, filed May 21, 1990,now abandoned.

TECHNICAL FIELD

The present invention relates to a method for producing an endless drivebelt from elastomeric belting. It also relates to an endless drive belt,and to a device for applying the method according to the invention.

DESCRIPTION OF THE PRIOR ART

Open-ended elastomeric belting complete with embedded load-carryingcording made of such high-strength materials as cotton, rayon, polyesterand the like is well-known and has been extensively used in the past.The difficulties with this type of belting arise, however, when lengthsof pre-formed open-ended belting, cut to size, have to be joined to formendless belts. While the ends of a thermoplastic belting body are easilyjoined by application of heat or adhesives, the problem arises with theload-carrying cords. Here, any number of methods have been proposed,involving splices, overlaps, overlays, inlays, etc., none of which givereally satisfactory results, producing as they do regions of differentstiffness, increased minimum bending radii, vibrations and noise, and,altogether, reduced belt strength and service life, as well as increasedwear of pulley bearings.

In view of the above, methods have been devised whereby an endless layerof reinforcing and load-carrying material is applied to the elastomericbelting after the latter has been joined to form an endless belt.

Thus, in German Patent No. 2,361,244 and U.S. Pat. No. 3,847,029 Raydiscloses a method whereby an extruded strip consisting of a pluralityof belt body elements integrally arranged side by side is wrapped arounda core drum and welded to constitute an endless sleeve. After weldingthe sleeve is allowed to cool to ambient temperature. Each belt bodyelement is provided on its top surface with a channel confined by meansof projections into which is wound, in a plurality of turns, anopen-ended length of a load-carrying cord. The cord is coated duringwinding with a molten or liquid thermoplastic elastomer. By means of aheating device the coated cord is heated during winding to assure thatthe temperature of the thermoplastic elastomer is kept above its melttemperature at least until winding is finished. By the molten or liquidcoating the channels are substantially filled and the cord comes intodirect contact with the bottom surface of the channels recesses. Afterwinding and cooling below the melt temperature, the sleeve is sliced toproduce a plurality of separate belts.

This method, however, has several drawbacks. The apparatus required isheavy and complex. A given core drum can Produce only one belt size. Forthe liquid coating of the cord an applicator device is required such asan extruder which needs industrial support systems, room, etc. It isexpensive to install and run. This method is therefore not suitable forshops and factories, small and large, which in order to avoid the needto keep s costly stock for different drive-belt sizes, want to be ableto produce their own belts only if and when required.

As further drawback the molten or liquid elastomer will not fully remainin the channels as the core drum rotates during winding, but will dropfrom the underside thereof. The elastomer does not sufficiently adhereto the surface of the channels. The solidification conditions of thecord coating are uncontrolled and different for different turns of thecord.

SUMMARY OF THE INVENTION

It is one of the objects of the present invention to overcome thedraw-backs and disadvantages of the prior art method and to provide amethod for producing an endless drive belt from at least partiallyopen-ended elastomeric belting, that facilitates preparation of improvedendless drive belts of practically uniform strength and stiffness alongtheir entire length, by virtue of their load-carrying members beingjointless and that permits the use of relatively simple and inexpensiveequipment adapted to process pre-formed, open-ended components.

According to the invention this is achieved by providing a method forproducing an endless drive belt, comprising the steps of providing apre-formed compression member profile comprising a solid but softenableelastic material comprising a first elastomer, winding a pre-formedload-carrying member comprising a cord embedded in a solid butsoftenable elastic material comprising a second elastomer being fusiblewith said first elastomer, along and around a surface of saidcompression member belt thereby forming a layer comprising a pluralitybut at least more than one full turn, and simultaneously causing theturns of said wound layer of said load-carrying member to becomeintimately bonded to said surface of said endless compression memberbelt by applying mutual pressure between said turns and said surface andby selectively softening of surface layers of both said load-carryingmember and said endless compression member belt which are to come intocontact with each other just prior to coming into contact with eachother to at least such degree to allow the material of said surfacelayers under the mutual pressure applied to fuse and further to allowsaid turns to be at least partially embedded or impressed in saidsurface of said endless compression member belt.

It is a further object of the invention to provide a drive belt easilyproduced at any required size and at minimal costs and capital outlay.

According to the invention, this is achieved by providing an endlessdrive belt, comprising a compression member belt having a surface andcomprising a solid but softenable elastic material comprising a firstelastomer, and a load-carrying layer, constituted by a plurality but atleast more than one full turn of load-carrying member wound along andaround said surface of said compression member belt, said load-carryingmember comprising a cord embedded in an envelope comprising a solid butsoftenable elastic material comprising a second elastomer being fusiblewith said first elastomer, wherein said turns of said wound layer ofsaid load-carrying member are intimately bonded to said surface of saidcompression member belt, the interface between said turns and saidsurface comprising fused material from both an adjacent surface layer ofsaid envelope of said cord of said load-carrying member and an adjacentsurface layer of said surface of said compression member belt, saidturns being at least partially embedded or impressed in said surface.

It is yet another object of the present invention to provide arelatively simple and inexpensive device for carrying out the methodaccording to the invention which would permit in-house preparation ofdrive belts of any size as an economical proposition.

According to the invention, this is achieved by providing a device forproducing an endless drive belt from pre-formed members, said members atleast including a compression member belt and a load-carrying membercomprising a solid but softenable elastic material each, the devicecomprising a belt-building pulley having a width just matching the widthof at least one single compression member belt, drive means for rotatingsaid belt-building pulley, an idler pulley arranged in alignment withsaid belt pulley and at a variable center distance therefrom, means toadjust said variable center distance to provide an appropriate tensionin said compression member belt when mounted between said belt-buildingpulley and said idler pulley, pressurizing means for the application ofmutual pressure between said compression member belt and saidload-carrying member during winding thereof onto the outer surface ofsaid compression member belt by rotation of said belt-building pulley,softening means for selectively softening of surface layers of both saidload-carrying member and said compression member belt which are to comeinto contact with each other during winding just prior coming intocontact with each other to at least such degree to allow the material ofsaid surface layers under the mutual pressure applied to fuse andfurther to allow the turns of said load-carrying member to be at leastpartially embedded or impressed in said surface of said compressionmember belt.

BRIEF DESCRIPTION OF THE DRAWINGS

Preferred embodiments of the invention will now be described withreference to the following illustrative figures. In the drawings:

FIG. 1 is a perspective view showing the cross section of a drive beltproduced by the method according to the invention;

FIG. 2 shows a perspective view of a load-carrying member according tothe invention;

FIG. 3 is a perspective view of an embodiment incorporating a tensionmember with load-carrying member;

FIG. 4 illustrates a butt joint joining the ends of the compressionmember of a V-belt profile;

FIG. 5 is a schematic presentation of a device according to theinvention;

FIG. 6 is a partial view of the molding pulley of the device, and

FIG. 7 is a side view of the molding pulley, the guide block and thehot-air blower.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring now to the drawings, there is seen in FIG. 1 a firstembodiment of a plain V-belt produced by the method according to theinvention.

The V-belt of FIG. 1 comprises a body member, known in the art ascompression member, 2, and of a load-carrying layer 4 composed ofseveral turns of a load-carrying member 6 which turns, in a method stepto be discussed further below, have been intimately bonded both to thecompression member 2 and to one another. The compression member 2 ismade of or at least comprises a solid but softenable elastic materialcomprising a first elastomer. The load-carrying member 6 consists of areinforcing, high-strength cord 8 embedded in an envelope 10 made of orat least also comprising a solid but softenable elastic materialcomprising a second elastomer. Both said first and said secondelastomers are fusible with each other and are preferably thermoplasticelastomers such as polyurethanes (e.g. ESTANE by B. F. Goodrich),polyesters (e.g. HYTREL by Dupont), olefins (e.g. LEVAFLEX by Bayer) oralloys (e.g. SANTOPRENE by Monsanto).

Further seen is a so-called tension member 12, an optional componentbonded to the layer 4 of load-carrying members 6. The tension-member 12is also made of or at least comprises solid but softenable elasticmaterial comprising a third elastomer. Said third elastomer is fusiblewith at least said second elastomer and is preferably a thermoplasticelastomer of the kind as mentioned above, too.

While the tension member 12 in FIG. 1 is flat and smooth, tensionmembers in, e.g., conveyor-belt applications may have non-rectangular,e.g., triangular cross sections, or may have a riffled surface.

The load-carrying member 6 represented in FIG. 2, pre-formed byconventional methods in open-ended reels, has a circular cross sectionand consists of a reinforcing cord 8 firmly embedded and enveloped inthe above defined material 10 being compatible with material of thecompression member 2, which has also been defined above. The cord 8itself is made of high-strength materials such as cotton, rayon,polyester or aramid. Prior to embedding, the reinforcing cord 8 isadvantageously coated with a primer such as an aqueous epoxy primer andan adhesive such as a polyurethane adhesive and may also be thermallytreated for improved mechanical properties.

In certain applications, the cord 8 may be produced by twisting orbraiding together at least two materials: one of high strength and oneof good natural adhesion to the material of the envelope 10.

Embodiment of FIG. 3 incorporates the tension member 12 with theload-carrying member 6 to a single pre-formed member.

As already mentioned, all belt components: the compression member 2, theload-carrying member 6 and the (optional) tension member 12 arepre-formed by conventional methods such as extrusion, casting ormolding. Setting out from these preformed components, the methodaccording to the invention proposes the following steps:

A piece of compression member 2 is cut to the required length asdetermined by the respective pulley diameters and center distance.Preferably, the free ends of the piece are then joined to form as inFIG. 4 for example, a butt joint 14. The actual joining method may beselected to best suit the properties of the material of the compressionmember 2 and the availability of tooling. Thus, for thermoplasticmaterials, joining can be effected by having both ends contact hot plateor blade and then pressing the ends one against the other.Alternatively, a jet of hot air may be used or indeed any of the bondingtechnologies known which combine heat and pressure.

Another alternative for bonding is the use of adhesives, a method whichis not restricted to thermoplastic materials and may be applied also tovulcanized rubber, cross-linked polyurethane and others.

Other embodiments of the compression member are possible includingmolded endless members, open ended (without bond) members, etc.

After the open-ended piece of compression member has been turned into anendless belt by the above discussed joining of the ends, the loadcarrying member 6, drawn off a reel of the pre-formed component is woundin a continuous spiral with the turns close to each other onto, andlongitudinally around, the top surface 16 (FIG. 4) of the compressionmember 2, preferably substantially covering the width of the latter.Pressure forcing the load-carrying member 6 onto the belt surface 16 isapplied during this winding. The pressure may be produced by keeping theload-carrying member 6 taut while winding or by means of at least onefloating roller. During the winding stage in addition surface layers ofboth said load-carrying member and said compression member belt whichare to come into contact with each other are simultaneously andselectively softened just prior to coming into contact with each other.Said softening is carried out by the application of heat and/or of anadhesive.

The heat or adhesive, and pressure, applied causes an intimate bond tobe formed between a) the load-carrying member 6 as it is being laid downand the belt surface, and b) between the new turn and the previous turnof the load-carrying member 6. After the above-described application ofthe load-carrying layer 4, the interface between the load-carryingmember 6 of this layer and the belt surface 16 consist in fact of fusedmaterial from both the softened surface layer of the cord envelope 10and the softened material of the belt surface. Also, due to the windingpressure applied, the load-carrying members 6 will be at least partiallyembedded or impressed in the belt surface 16, the groove-likeimpressions 9 being clearly seen in FIGS. 1 and 6. The load-carryingmembers should be impressed in the belt surface to a degree of at least20%. Preferably no hollow spaces should remain between adjacent turns.

Preferably the thickness of the softened surface layer of theload-carrying member 6 is smaller than the thickness of the envelope 10of cord 8 in order not to deteriorate the adhesion between the cord andits envelope, which preferably has been optimized during the pre-formingstage of the load-carrying member. To achieve this, a highly selectiveand well timed application of heat and/or of an adhesive is required.

It is further preferred to have the amount of heat and/or of an adhesiveand the amount of pressure applied adjusted in such way to obtain anoptimal winding velocity.

Yet another method of producing the load-carrying layer 4 is thesimultaneous winding of several load-carrying members 6 Producingmultiple ends and thus reducing the required time for preparing a drivebelt.

A similar procedure is followed for applying the optional tension member12, except that this member is obviously not applied spirally, butstraight and in most cases in the form of one turn only. Using a memberas shown in FIG. 3 the load-carrying member and the tension member areapplied in one step only.

The method according to the invention will be better understood inconjunction with the device represented in the schematic drawings ofFIGS. 5 to 7, the task of which device is to provide the belting with acontinuous, in fact endless, load-carrying layer. There is seen abelt-building or molding Pulley 18 (FIGS. 5,6), the groove profile ofwhich matches the flanks 13 (FIG. 4) of the compression member 2, andwhich can be rotated either manually or, preferably, by means ofvariable-speed gearmotor 22. A second, idler, pulley 24 is arranged at adistance from, and in alignment with pulley 18. The idler pulley 24 isrotatably mounted on a block 26 provided with an internal thread andriding on a screw 28 having one degree of freedom in rotation only.Thus, rotating the screw 28 (by means of a handle 30) will cause theblock 26, including the idler pulley 24, to perform a translatorymovement, permitting the center distance between pulley 18 and the idlerpulley 24 to be varied. The bar 32 passing through a fork-likeprojection 34 attached to the block 26 prevents the latter from rottingabout the screw 28, while allowing the above translatory movement. Thescrew 28 and the bar 32 are mounted between brackets 33 which areobviously stationary relative to the idler pulley 24 and its mountingblock 26.

Further seen is a guide block 36 (see also FIG. 7) through which passesthe load-carrying member 6, drawn off a supply reel 37, on its way to bewound onto the belt, as will be explained in greater detail furtherbelow.

The guide block 36 is capable of a translatory movement in a directionparallel to the axis of a lead screw 38 which, when rotated, will causethe block 36 to perform such a translatory movement. The lead screw 38is either operated manually or, preferably, is connected to anothervariable-speed motor 40, the speed of which can be maintained at apredeterminable ratio relative to the gear-motor 22 driving the moldingpulley 18, by means of a control element 42. The importance of thecontrollability of this ratio will be explained further below.

Mounted below the guide block 36 either fixedly or taking part in thetranslatory movement of the latter, there is seen a blower 44 producinga jet of hot air which nozzle 46 directs towards the point where theload-carrying member 6, having Passed the guide block 36, makes contactwith the belt surface. Alternatively, the heat required for the bondingprocess could also be provided by a source of concentrated radiatingheat. A source of concentrated ultrasonic vibrations or by source ofconcentrated electromagnetic oscillations. In the latter case it is,however, required that the material of the cord envelope and/or of thecompression member belt comprises small metallic particles.

The compression member 2, having been produced by any of theabove-mentioned procedures, is mounted on the two pulleys, the moldingpulley 18 and the idler pulley 24 which, by turning handle 30 are thenmoved part until the compression member belt is fairly tight. The end ofthe load-carrying member 6 is then drawn off the supply reel 37,threaded through the guide block 36 (which has been set to the initialtransversal position, i.e., opposite the left edge of the belt) andattached to the belt, e.g., by being spot-welded to the belt. Thehot-air jet (or the respective different heat source) is now turned onand the molding pulley 18 set rotating by actuating the gear motor 22,setting in motion the belt 2, and, thereby dragging long theload-carrying member 6 which, heated by the jet, is bonded to theequally heated (and thereby softened) belt surface. The tightnessrequired for orderly winding is produced by the counterpull generated byfriction offered to the moving load-carrying member as it passes throughthe guide block 36. Bonding pressure is produced by the same counterpulldue to the deflection of the load-carrying member 6 as it makes contactwith the arched portion of the belt surface in the pulley 18. As alreadymentioned the required pressure could as well or in addition be appliedby at least one floating roller (not shown).

As the belt 2 starts moving, drawing along the load-carrying members,the lead screw 38 has also started to rotate, and slowly carries theguide block 36 towards the right. Thus, while rotation of the pulley 18,i.e., movement of the belt, causes the load-carrying member 6 to bewound around the belt 2, the transverse movement of the guide block 36produces the spiral path that will produce an orderly load-carryinglayer 4.

The required relationship between the rotational speed of the pulley 18and the linear speed of the guide block 36 is not only a function of thewidth of the belt 2 and the diameter or width of the load-carryingmember 6, but also of the surface speed of the belt and on belt length.Hence the importance of the control element 42.

Another configuration calls for stepping action of the guide block 36 atthe completion of each revolution of the compression member 2.

Application, to the now reinforced belt of the optional tension member12 follows similar lines, except that a different guide block isrequired and that the latter performs no transverse movement, being infixed alignment with the belt 2. Also, while the nozzle 46 produces arather narrow hot-air jet, the relatively wide tension member requires awide and flat jet (or a number of pointed jets).

For use of the device with adhesives, the blower assembly 44, 46 isreplaced by an adhesive dispenser. Such dispenser could of course aswell be provided in addition to a heat source.

Although the embodiments given to illustrate the inventions describes aplain V-belt, it should be understood that the method and devicediscussed are also suitable for the production of other drive-belttypes, such as cogged V-belts, flat belts and synchronous or timingbelts.

It will be evident to those skilled in the art that the invention is notlimited to the details of the foregoing illustrative embodiments andthat the present invention may be embodied in other specific formswithout departing from the spirit or essential attributes thereof. Itwould for example also be possible as a first step to spirally wind aload-carrying member on at least one mounting pulley having asubstantially flat outer surface, thereby forming a layer comprisingplurality but at least more than one full turn and as a second step towind just one full turn of a pre-formed open-ended compression memberprofile along and round the outer surface of said layer of saidload-carrying member, thereby simultaneously causing said compressionmember profile in the same manner as explained above to becomeintimately bonded to said surface of said turns of said wound layer ofsaid load-carrying member. The present embodiments are therefore to beconsidered in all respects as illustrative and not restrictive. Allchanges which come within the meaning and range of equivalency of theclaims are therefore intended to be embraced therein.

What is claimed is:
 1. A device for producing an endless drive belt frompreformed members, said members including a compression member belt anda load-carrying member, each member comprising a solid but softenableelastic material, the device comprising:a belt-building pulley having awidth just matching the width of at least one single compression memberbelt; drive means for rotating said belt-building pulley; an idlerpulley arranged in alignment with said belt pulley and at a variablecenter distance therefrom; means to adjust said variable center distanceto provide an appropriate tension in said compression member belt whenmounted between said belt-building pulley and said idler pulley;pressurizing means for the application of mutual pressure between saidcompression member belt and said load-carrying member during windingthereof onto the outer surface of said compression member belt byrotation of said belt-building pulley; and softening means forselectively softening the surface layers of both said load-carryingmember and said compression member belt which are to come into contactwith each other during said winding just prior to coming into contactwith each other to at least such degree as to allow the material of saidsurface layers under the applied mutual pressure to fuse and further toallow the turns of said load-carrying member to be at least partiallyimpressed into said surface of said compression member belt.
 2. A deviceas claimed in claim 1, wherein said softening means are heater means andare disposed in such a way as to be capable of applying the heatsimultaneously and selectively to said load-carrying member and to saidsurface of said compression member belt in the proximity of the point atwhich the load-carrying member during winding thereof onto said surfaceof said compression member belt comes into contact with said surface. 3.A device as claimed in claim 2, wherein said heater means comprises anelectric blower and a nozzle producing a jet of hot air.
 4. A device asclaimed in claim 2, wherein said heater means comprises a source ofconcentrated radiating heat.
 5. A device as claimed in claim 2, whereinsaid heater means comprise a source of concentrated electromagneticoscillations.
 6. A device as claimed in claim 2, wherein said heatermeans comprise a source of concentrated ultrasonic mechanicalvibrations.
 7. A device as claimed in claim 1, wherein said softeningmeans includes dispenser means for applying an adhesive at least to saidload-carrying member just prior to the disposition thereof onto saidsurface of said compression member belt.
 8. A device as claimed in claim1, wherein said softening means includes heater means and dispensermeans for applying an adhesive.
 9. A device as claimed in claim 1,wherein said pressurizing means includes guiding means for guiding andkeeping taut the load-carrying member during winding thereof onto saidcompression member belt, said guiding means being adapted to offer aresistance to the movement of said load-carrying member therethrough.10. A device as claimed in claim 1, wherein said pressurizing means arefloating rollers.
 11. A device as claimed in claim 1, further comprisingguide means for guiding said load-carrying member during winding thereofonto said compression member belt.
 12. A device as claimed in claim 11,further comprising second drive means to impart to said guide meanstranslatory movement during rotation of said belt-building pulley in adirection perpendicular to the longitudinal extent of said compressionmember belt as mounted between said belt-building pulley and said idlerpulley.
 13. A device as claimed in claim 11, further comprising means tocontrol the relationship between the rotational speed of saidbelt-building pulley and the speed of the translatory movement of saidguiding means.